1. Field of the Invention
The invention relates to a matrix pin print head, which is adjustable or is adjusted at a fixed distance relative to a print support, where a recording substrate rests on the print support, and where an ink ribbon is disposed and guided in front of the print pins and between the matrix pin print head and the recording substrate, where drives are provided together with the print pins or individually coordinated to each print pin, where an electromagnetic coil is associated in each case with the drives, and wherein each print pin is movable within one stroke from a rearward withdrawn position into a forward extended position and back.
2. Brief Description of the Background of the Invention Including Prior Art
In a special category of matrix pin print heads the drive comprises in each case a clapper armature driving the print pin. In a rearward rest position, all clapper armatures rest with a radially inner clapper armature end at a joint face and all radially outer clapper armature ends transfer the drive force. Furthermore, the path of each print pin up to a forward extended print position corresponds to the clapper-armature stroke path.
The invention is further concerned with a method for controlling the print pins of a matrix pin print head for the purpose of adaptation to the number of copies to be printed and/or for the purpose of adapting the print frequency in the sense of a change of the print speed of a matrix printer.
Such matrix pin print heads in matrix pin printers are known from the U.S. Pat. No. 4,230,038 for the setting of all armatures to one single operating air gap and from the German Patent Application Laid Open DE-OS 3,412,855 for a permanently fixed setting of the operating air gap between magnet yoke and clapper armature.
Modern matrix pin print heads are operated today with pin frequencies of from 1000 to 3000 Hz. The print pin and the drive element of the print pin are therefore furnished with a lowest possible mass for physical purposes. On the other hand, a high number of readable copies are required from matrix pin printers which requires a high impact force of the individual print pins.
A high impact force of each individual print pin would be possible in case of a correspondingly large mass of the moving parts, i.e. the print pin and the corresponding drive element, or, alternatively, a high impact energy would be generated via a large pin stroke path in case of a large acceleration. The two requirements, the high pin frequency and the high number of copies of a printed substrate piece, represent technically opposite and contradictory requirements relative to a matrix pin print head. Therefore, it was necessary to make compromises in the construction which, however, have not been satisfactory so far.
The performance and capacity data of a matrix pin print head are determined, amongst others, by the following parameters:
dimension of the magnet circuit, PA1 material qualities of the magnet yoke with armature, PA1 characterizing values of the electromagnetic coil, PA1 moments of mass inertia of moving mass, and PA1 dimension of the operating air gap.
After fixing of the dimensions of a matrix pin print head, theoretically after its assembly and mounting, only the operating voltage and the current feed curve can be changed from the outside. Such an influence however does not result in the desired effect after a matrix pin print head has been constructed with permanently fixed dimensions.